Russia is at the brink of a major HIV epidemic. While the total number of HIV infections in Russia is still much smaller than in many other world areas, the number of cases diagnosed in just the past year exceeds the total number diagnosed in all prior years. Soaring STD rates--up 62-fold since 1988--widespread drug use, economic upheaval, joblessness, and limited resources for dealing with social health problems portend a great Russian HIV epidemic. This application proposes a consortium of the Center for AIDS Intervention Research (CAIR) at the Medical College of Wisconsin, Yale University School of Public Health, and the Biomedical Center on AIDS/St. Petersburg State University (SPSU) in Russia to serve as an AIDS Collaborative Team (ACT) in the NIMH Cooperative Agreement. Our investigational team developed the HIV prevention approach of engaging popular opinion leaders (POLs) to serve as behavior change agents and has conducted research on this intervention model for 12 years; our team has extensive experience implementing community-level HIV prevention interventions, undertaking international HIV prevention programs, and conducting STD research in resource-poor countries. This proposal also takes advantages of relationships in Russia established through an existing Fogarty AIDS prevention research training program at SPSU. Our ACT's target population is young adults, 18 to 25 years old, who live in twelve low-income "dormitories" in St. Petersburg. Six of the domitory sites will be randomized to the intervention and 6 to the comparison condition. Each dormitory site, similar to a low-income housing development in the U.S., provides residence to young adults who are attempting to gain work skills. Prior research indicates very high rates of unprotected sex in this population. Following a period of ethnographic studies, we will collect baseline risk behavior and STD biological data from all residents in both sites' dormitories. All STDs detected will be treated. A one- year intervention that identifies and engages POLs in each intervention condition dormitory site to function as behavior change agents to others in the same worker dormitory will then be undertaken following methods used successfully in our past studies. The intervention is expected to strengthen norms and encourage risk reduction among members of the intervention site population. Effectiveness of the intervention will be determined by examining change in risk characteristics and STD rates at a 12-month followup point in the intervention and comparison site populations using both community-level and individual-level analyses.